Sun-vibration Study Of The Star Eta Bootis

The great achievements in research of the Sun's interior structure and evolution by using helioseismology encouraged people to study the fixed stars with oscillation phenomenon similar to that of the Sun. Researchers hope that they can analyze and study these stars' oscillation by using a method similar to helioseismology to know more about their interior structure and evolution, thus to verify and expand our knowledge in this field from a wider range and a higher precision. So, the study of solar-like oscillations came from helioseismology combine with the stellar structure and evolution. Because the oscillation frequencies can measure more precision than other parameters of the star, through this method can study more information from the star than other methods.The subgiant HR 5235, better known as eta Bootis, is a well-studied bright star (V=2.68) of spectral type GO IV and a good candidate for asteroseismic studies since theory models (Christensen-Dalsgaard & Frandsen 1983; Houdek et al. 1994) predict that subgiants should have somewhat larger oscillation amplitudes than the Sun.Eta Bootis is a binary systems with a brown dwarf secondary. All the existent studyabout eta Bootis all ignored the secondary and only attention the main, so all theirs calculations used the single star structure and evolution code. We think that the inconsistencies between the existent theories calculated results of eta Bootis with the observational data may be came from this simplification. So, in this paper, our main aim is use the binary structure and evolution code that considered more veritable factors to calculate eta Bootis models again. We also compare our results with the observational data and others theory results, and find the best model of eta Bootis.The binary evolution code we used in the calculations of this paper consider all the effects between the binaries, such as the rotating, the exchange of material betweenthe binaries, the mass loss of stellar wind and so on. We all analysis others effects to eta Bootis structure and evolution in this paper, and find the best models for eta Bootis binary system in non-oscillations limits. In our oscillation frequencies calculations, we compare our results with the observational oscillation data of Kjldsen et al. (2003).